Sugarcane Clones Derived through Immature Leaf Callus Cultures

The biotechnological potential of pectinolytic fungi isolated from citrus fruits was studied. Seventy five fungal isolates were isolated from decayed citrus fruits. All of these isolates were screened for their pectinolytic activity. Thirty six out of seventy five isolates proved to have pectinolytic activity. These isolates were identified and classified into twenty strains belonging to eleven species appertaining to six genera of fungi. Aspergillus was the first predominant genus encountering in 50% of the total isolates. The second higher incidence rate was recorded for the genera of Cladosporium and Penicillium. Evaluation of the twenty strains for their ability to produce the exoplygatacturonase enzyme indicated that, A. niger AUMC 4156 and P. oxalicum AUMC 4153 were the highest producers of this enzyme and their potentiality were superior to that of the imported strain A. niger NRRL 337, known as the highly enzyme producer. Studying the environmental and nutritional factors leading to maximum exo-polygalacturonase production by these three strains showed that, the optimum incubation temperature was 40°C in case of P. oxalicum AUMC 4153 and 30°C in case of A. niger AUMC 4156 and A. niger NRRL 337. The optimum pH values were 5, 6 and 7 for A. niger AUMC 4156, A. niger NRRL 337 and P. oxalicum AUMC 4153, respectively. The optimal incubation period was five days and the best inoculum size was 2% for all the studied fungal strains. Pectin at concentration of 4% proved to be the best carbon source for all fungal strains, followed by starch in case of Aspergillus and by sucrose in case of Penicillium. Also, it was found that, the maximum enzyme production was attained by using of 4% yeast extract as the sole nitrogen source for all the studied fungi.